﻿Pressure, 
  and 
  Latent 
  Heat 
  of 
  Vaporization. 
  389 
  

  

  References. 
  

  

  I, 
  Andrews, 
  Th., 
  Quart. 
  Journ. 
  Chem. 
  Soc, 
  London, 
  i, 
  27, 
  1849. 
  

  

  II-XI, 
  Berthelot, 
  Comptes 
  Rendus, 
  Ixxviii, 
  162, 
  1874; 
  Annales 
  de 
  Chimie 
  et 
  de 
  

   Physique, 
  v, 
  vi. 
  145, 
  1875. 
  III. 
  Comptes 
  Rendus, 
  lxxxii, 
  119, 
  1876. 
  IV, 
  ibid., 
  

   p. 
  122. 
  V, 
  Annales 
  de 
  Chimie 
  et 
  de 
  Physique, 
  v, 
  xii, 
  529, 
  1877. 
  VI, 
  ibid., 
  p. 
  535. 
  

   VII, 
  ibid., 
  p. 
  550. 
  VIII, 
  Comptes 
  Rendus, 
  lxxxviii. 
  52, 
  1879. 
  IX, 
  ibid., 
  lxxxix, 
  

   119, 
  1879. 
  X, 
  ibid., 
  xc, 
  1510, 
  1880. 
  XI, 
  ibid., 
  xciii, 
  118, 
  1881. 
  

  

  XIa, 
  Berthelot 
  and 
  Matignon, 
  Bull. 
  Soc. 
  Chim., 
  Ill, 
  xi, 
  p. 
  867, 
  1894. 
  

  

  X-XIV, 
  Berthelot 
  and 
  J. 
  Ogier, 
  Ann. 
  Chim. 
  Phys., 
  V, 
  xxiii, 
  201, 
  1881. 
  XI, 
  

   Comptes 
  Rendus, 
  xcii, 
  769, 
  1881. 
  XII, 
  Ann. 
  Chim. 
  Phys., 
  V, 
  xxx, 
  382, 
  1883. 
  

   XIII, 
  ibid., 
  p. 
  400. 
  XIV, 
  ibid., 
  p, 
  410. 
  

  

  XV 
  Brix, 
  TV, 
  PoggendorfE's 
  Annalen, 
  lv, 
  341, 
  1842. 
  

  

  XVI, 
  Dieterici, 
  C 
  , 
  Wiedemann's 
  Annalen, 
  xxxvii, 
  494, 
  1889. 
  

  

  XVII, 
  Favre 
  and 
  Silbermann, 
  Ann. 
  Chim. 
  Phys., 
  Ill, 
  xxxvii, 
  461, 
  1853. 
  

   XVIIa. 
  Nadejdine, 
  Exaer, 
  Repertorium, 
  p. 
  446, 
  1894. 
  

  

  XVIIli 
  Ogier. 
  Comptes 
  Rendus, 
  xx, 
  922, 
  1881. 
  XIX, 
  ibid., 
  xcvi, 
  646, 
  1883. 
  

   XlXa, 
  Longuinine, 
  Comptes 
  Rendus, 
  cxix, 
  601, 
  1894. 
  

  

  XX, 
  Person, 
  Comptes 
  Rendus, 
  xxiii, 
  343, 
  1846. 
  

  

  XXI, 
  Petit, 
  Ann. 
  Chim. 
  Phys., 
  VI, 
  xviii, 
  145, 
  1889. 
  

  

  XXII, 
  Ramsay 
  and 
  Young, 
  Philosophical 
  Transactions, 
  clxxviii, 
  A, 
  313, 
  1887. 
  

  

  XXIII, 
  Regnault, 
  Memoires 
  de 
  l'Academie, 
  xxvi, 
  761, 
  1862. 
  XXIV, 
  Id., 
  Ann. 
  

   chim. 
  phys.. 
  IV, 
  xxiv, 
  375, 
  1871. 
  

  

  XXV 
  Schall, 
  Ber. 
  deutsch. 
  chem. 
  Ges., 
  xvii, 
  2199, 
  1884. 
  

  

  XXVI, 
  Schiff, 
  R., 
  Liebig's 
  Annalen, 
  ccxxxiv, 
  338, 
  1886. 
  

  

  XXA 
  r 
  II, 
  Winkelmann, 
  A., 
  Wiedemann's 
  Annalen, 
  ix, 
  208 
  and 
  358, 
  1880. 
  

  

  XXVIII, 
  Wirtz, 
  K., 
  Wiedemann's 
  Annalen, 
  xl, 
  438, 
  1890. 
  

  

  It 
  is 
  not 
  easy 
  to 
  make 
  an 
  estimate 
  of 
  the 
  accuracy 
  of 
  some 
  

   of 
  the 
  data 
  recorded 
  in 
  the 
  foregoing 
  table 
  ; 
  the 
  determina- 
  

   tions 
  have 
  been 
  made 
  by 
  scientists 
  employing 
  different 
  methods 
  

   and 
  different 
  preparations, 
  and 
  hence 
  the 
  same 
  degree 
  of 
  exacti- 
  

   tude 
  cannot 
  be 
  attributed 
  to 
  the 
  work 
  of 
  each. 
  Two 
  principal 
  

   sources 
  of 
  error 
  are 
  encountered 
  in 
  the 
  determinations 
  of 
  latent 
  

   heats 
  of 
  vaporization 
  : 
  the 
  method 
  may 
  not 
  be 
  accurate 
  : 
  the 
  

   liquid 
  may 
  not 
  be 
  pure. 
  As 
  a 
  rule, 
  in 
  the 
  same 
  investigation 
  

   both 
  these 
  sources 
  of 
  error 
  are 
  met 
  with 
  ; 
  that 
  is, 
  those 
  investi- 
  

   gators 
  who 
  have 
  worked 
  by 
  faulty 
  methods 
  have 
  also 
  not 
  always 
  

   taken 
  liquids 
  of 
  requisite 
  purity. 
  Nearly 
  all 
  the 
  earlier 
  deter- 
  

   minations 
  are 
  subject 
  to 
  this 
  criticism, 
  as 
  those 
  by 
  Person, 
  Brix, 
  

   and, 
  to 
  some 
  extent, 
  especially 
  as 
  regards 
  the 
  purity 
  of 
  the 
  

   products, 
  those 
  by 
  Favre 
  and 
  Silbermann. 
  Andrews' 
  work 
  

   which, 
  as 
  far 
  as 
  the 
  method 
  is 
  concerned, 
  is 
  remarkably 
  accu- 
  

   rate 
  for 
  the 
  time 
  when 
  it 
  was 
  done, 
  has 
  been 
  performed 
  in 
  

   some 
  cases 
  with 
  impure 
  liquids 
  ; 
  this 
  is 
  especially 
  true 
  of 
  the 
  

   ethers 
  investigated 
  by 
  him. 
  Schiff 
  states 
  how 
  difficult 
  it 
  is 
  to 
  

   obtain 
  in 
  a 
  state 
  of 
  great 
  purity 
  the 
  more 
  volatile 
  ethers. 
  

   Thus, 
  for 
  ethyl 
  formiate, 
  a 
  liquid 
  very 
  hard 
  to 
  purify, 
  Schiff 
  

   found 
  the 
  heat 
  of 
  vaporization 
  to 
  be 
  92*15 
  cal., 
  while 
  Andrews 
  

   found 
  105 
  '3 
  cal. 
  With 
  the 
  exception 
  of 
  the 
  ethers, 
  however, 
  

   Andrews' 
  determinations 
  may 
  be 
  regarded 
  as 
  very 
  precious 
  

   data. 
  Of 
  the 
  purity 
  of 
  the 
  liquids 
  used 
  by 
  Berthelot 
  and 
  by 
  

   Ogier, 
  it 
  is 
  especially 
  hard 
  to 
  form 
  an 
  opinion, 
  inasmuch 
  as 
  

   these 
  scientists 
  have 
  not 
  indicated 
  with 
  but 
  few 
  exceptions 
  

  

  